Molding compositions of polymers from trimeric phosphonitrilic compounds



United States Patent 3,454,409 MOLDING COMPOSITIONS OF POLYMERS FROM TRIMERIC PHOSPHONITRILIC COMPOUNDS Bernard Grushkin, Silver Spring, Md., assignor to W. R. Grace & Co., a corporation of Connecticut N0 Drawing. Original application July 9, 1964, Ser. No. 381,519, new Patent No. 3,370,089, dated Feb. 20, 1968. Divided and this application Dec. 29, 1967, Ser. No. 709,515

Int. Cl. C08g 9/24; C04b 35/14 US. Cl. 10669 8 Claims ABSTRACT OF THE DISCLOSURE A molding compound prepared from an organic substituted trimeric phosphonitrilic compound in which substituted alkyl groups may contain from 1 to 3 carbon atoms. The phosphonitrilic compound is polymerized and fillers are added to form high temperature resistant, semiorganic resins and ceramic type materials.

may be treated with ammonia to obtain the corresponding amido derivative having the formula This ammoniated derivative may be deaminated at elevated temperatures to obtain a highly crosslinked inonganic type polymer which is resistant to high temperatures but which is highly insoluble and diflicult to work.

To modify the ultimate properties of inorganic type polymers and thereby extend the applications and utilities therefore, it is frequently desirable to introduce organic type linkages into a basically inorganic polymer system.

It is therefore an object of the present invention to provide a novel organic modified phosphonitrilic polymer intermediate having specific utility in the preparation of high temperature semi-inorganic polymer systems.

It is another object to provide a novel organic modified phosphonitrilic polymer.

It is a further object to provide novel filled organic modified phosphonitrilic polymer compositions which may be molded and cured to form high temperature resistant articles.

It is still another object to provide useful ceramic type articles prepared from the present novel filled organic modified phosphonitrilic resins.

These and still further objects of the present invention will become more readily apparent to one skilled in the art from the following detailed description and/or specific examples.

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Broadly, the present invention contemplates a compound of the following formula:

4: NHCHrOR HOHzCHN N N NHCHzOH l 0 \N/ wherein R is lower alkyl having 1-3 carbon atoms, ie., methyl, ethyl, propyl, or isopropyl, which may be polymerized at high temperatures to obtain novel polymers which contain the following type linkages:

In the above structural Formulas II and III, and frequently hereinafter, the symbol will be used to designate the cis and trans-2,4,6-triphenyltriphosphonitrile ring containing 3 open valences.

The 2 type linkages II and III and the trifunctional character of I lead to the formation of a polymer which contains the following repeating units:

or both, wherein n and m have values of from about 2 to about 11.

More specifically, I have found that good yields of Compound I may be prepared by reacting cis and/or trans 2,4,6-triphenyl-2,4,6-triaminotriphosphonitrile with with formaldehyde (or a formaldehyde yielding compound) in the presence of a lower aliphatic alcohol, such as ethanol. Compound I may then be heated to a temperature of about 200 C. to obtain a crosslinked polymer containing the repeating units illustrated as IV or V above and having a molecular weight of from about 3,000 to about 5,000. These polymers can be used to fabricate parts which are stable at temperatures up to about 400 C.

Typically (but not exclusively) the polymers prepared by the practice of the present invention may be illustrated as 6 membered units having the following general structure:

lTIHCHaOR in which R is hydrogen, methyl, ethyl, propyl, isopropyl, or mixtures of hydrogen and one of the lower alkyl group, depending upon the alcohol employed in the reaction.

In view of the fact that the present polymers may possess two types of linkages, and the inorganic monomer unit is trifunctional, it is obvious that the present polymers comprise a mixture of polymeric structures, all of which cannot be illustrated herein.

However, all of the present polymers may be defined as (1) being polymers formed by the self-condensation of monomeric Compound I, (2) containing repeating units IV and V, and (3) having a molecular weight of from about 3,000 to about 5,000.

Compound I above is prepared by reacting cis or trans- 2,4,6-triphenyl-2,4,6-triaminotriphosphonitrile with formaldehyde (or a formaldehyde source) in the presence of lower alkanol, ethanol at a temperature of from about 60 to about 80 C. The 2,4,6-trichloro-2,4,6-triaminotri phosphonitrile used in the practice of the present invention may be conveniently obtained by ammoniating 2,4,6- trichloro-2,4,6-triphenyltriphosphonitrile with an excess of ammonia at about room temperature and preferably in the presence of an inert solvent such as chloroform. The 2,4,6trichloro-2,4,6-triphenyltriphosphonitrile may be obtained by reacting phenyltetrachlorophosphorane with ammonium chloride in the presence of an inert solvent at elevated temepratures ranging from about 130 160 C.

To prepare Compound I above, from about 3 to about 4 moles of formaldehyde (or the equivalent amount of a formaldehyde yielding source) is admixed with each mole of 2,4,6-triamino-2,4,6-triphenyltriphosphonitrile in lower alkanol. Ideally, but not necessarily, from about 10 to about 100 parts by weight of alkanol per part by weight reactants, are used in preparing the reaction mixture. The reaction mixture is adjusted in pH to about 5 to about 8 by the addition of an inorganic base such as sodium hydroxide. The presence of water in the reaction mixture does not alter the course of the reaction and from about 0.2 to about 0.8 parts by weight water per part by weight of reactants in the reaction mixture may be tolerated. Frequently, this water will be present along with the formaldehyde when an aqueous solution of formaldehyde is used.

The reaction mixture may be conveniently heated to reflux at about 6498 C. and heating continued thereat for a period of about 1 to about 3 hours to obtain substantial yields of the desired product I. As indicated above, the formaldehyde used in the present reaction may be standard 37% by weight aqueous formaldehyde solution, or may constitute an equivalent amount of formaldehyde yielding material such as paraformaldehyde or hexamethylenetetramine.

Subsequent to reaction, the desired product I is recovered by vacuum distillation of the solvent. The resultant product is recovered in the form of a solid which has a melting point of from about 112 to about 160 C. and an elemental analysis and molecular weight which indicates the compound of structure I given above.

Compound I obtained in the above procedure, may be converted into a useful semi-inorganic polymer by heating to a temperature in the range of from about 190 to about 230 C. A heating period of from about 1 to about 2 hours at the above temperature yields a soluble resin which possesses a molecular Weight of from about 3,000 to about 5,000. This resin is then subsequently 4 heated to a temperature of about 250 to about 280 C. and a cured resinous material is obtained which will not lose weight until heated to a temperature in excess of 400 C.

Preferably, but not necessarily, the curing of the present resins may be advantageously carried out in the presence of hexamethylenetetramine. The presence of the hexamethylenetetramine insures that methylol substitution and crosslinking resulting therefrom, is complete in the final resinous material. The presence of hexamethylenetetramine however, is not absolutely essential, and depending upon the degree of methylol substitution obtained in the preparation of Compound I above, excess hexamethylenetetramine may not be necessary for complete polymerization of the material.

It is frequently found that the present polymer illustrated as containing repeating units IV and V may be advantageously filled with inorganic materials such as silica, glass wool, vermiculite, asbestos, metal chips and so forth. Frequently it is found that from about 1 to about 4 parts by weight of filler may be incorporated per part by weight of resin. The filler is incorporated in the resin by mutually grinding the partially cured product, that is the resin obtained by heating Compound I to a temperature of from about 190 to about 230 C., and subsequently carrying out a post curing step under pressure at a temperature of from about 250 to about 280 C. Pressures on the order of from about 1,000 to about 3,000 lbs. per sq. in. may be advantageously used during the final curing steps. This curing, in the presence of filler, takes about 2 to about 10 hours at a temperature of from about 190' to about 280 C. The filled resin obtained by this process remains stable at temperatures up to about 400 C. The cured articles are tough, dense and extremely stable to atmospheric conditions.

The molded filled articles containing silica, glass wool, vermiculite or asbestos obtained above may be subsequently fired at temperatures ranging from about 800 to about 1,000 C. to obtain ceramic type materials which possess valuable high temperature resistant properties. Depending on the size of the article prepared, it was found that firing times of from about 4 to about 10 hours produce the desired results. Oeramic materials which contain from about 50 to about parts by weight of silica in the initial resin-filler composition, produce ceramic articles having particularly good thermal and mechanical properties.

Having described the basic aspects of the present invention, the following examples are given to illustrate embodiments thereof.

EXAMPLE I A 10 g. (24.1 mmoles) sample of trans-2,4,6-triphenyl- 2,4,6-triarninotriphosphonitrile was dissolved in 750 ml. of ethanol. The temperature of this mixture was raised to 55 C. and 5.9 g. of 37% by weight aqueous formaldehyde (72.3 mmoles) was added. The pH of the solution, which was initially 5, was adjusted to 8 by the addition of sodium hydroxide. A total of 50 ml. of water was present in the solution. The solution was then heated to reflux at 75-80 C. and held thereat for 2 hours. The resultant product was subjected to vacuum distillation until no more solvent was removed. In this manner 11.1 g. of the product having the following elemental analysis was prepared: C, 152.12; H, 5.80; N, 16.48; P, 17.57; 0, 8.03%. The empirical formula was determined to be C, 22.92; H, 30.42; P, 3.00; N, 6.24; O, 2.65; which corresponded very well to the Formula I (R=C H given above. The calculated molecular weight is 532. The determined molecular weight was 5 86.

EXAMPLE II A 3.0 g. sample of Compound I obtained in Example I was heated to 230 C. for 3 hours. During the heating step, mainly ethanol and water evolved from the reaction mixture. The polymer obtained by this process possessed a molecular weight of 3,400 and was deemed to be comprised of repeating structural units 1V and V illustrated above.

EXAMPLE III 2.6 g. of the polymer obtained in Example II was admixed with 7.4 g. each of silica fiber and glass wool. Samples were cured at 280 C. for 3 hours in a mold at a pressure of 2,000 p.s.i. The resultant samples had a hard dense appearance and did not lose weight until heated above 400 C.

EXAMPLE IV The filled articles obtained in Example III were fired at a temperature pr 950 C. After firing for a period of 8 hours, hard ceramic articles were obtained which possessed good thermal and mechanical properties.

EXAMPLE V 3.0 g. of polymer obtained in Example 11 was mixed with 7.0 g. of finely divided expanded Vermiculita in a ball mill. A molding was made from the mixture by compressing the mixture at 2,500 p.s.i. and subjecting it to a temperature of 280 C. for 3 hours. A hard dense piece resulted.

This was subsequently fired at 1,000 C. to give a hard, dense' ceramic material.

The above examples clearly illustrate that useful semiinorganic polymers may be obtained in accordance with the'teachings and examples set forth herein.

I claim:

1. A molding composition comprising from about 50 to about 20 parts by weight of polymer containing the following repeating structural units and having a molecular weight of from about 3,000 to about 5,000:

represents the triphenyltriphosphonitrile ring having 3 open valences, per part by weight of an inorganic filler.

2. The composition of claim 1 wherein said filler is particulate silica.

3. The composition of claim 1 wherein said filler is vermiculite.

4. The composition of claim 1 wherein said filler is glass fibers.

5. A method for preparing high temperature resistant molded articles which comprises admixing from about 1 by weight of polymer having the following repeating structural units:

and

LE: H H H2 H2 H wherein represents the triphenyltriphosphonitrile ring having 3 open valences, and having a molecular weight of from about 3,000 to about 5,000, and heating said mixture to a temperature of from about 230 to about 289 C. for a period of from about 2 to about 10- hours.

6. The method of claim 5 wherein said inorganic filler is finely divided silica.

7. The method of claim 5 wherein said inorganic filler is vermiculite.

8. A process for preparing a tough, high temperature resistant ceramic material by admixing silica with a polymer having a molecular weight of from about 3,000 to about 5,000 and comprising the following repeating structural units:

represents the triphenyltriphosphonitrile ring having 3 to about 4 parts by weight of an inorganic filler per part open valences, curing said mixture by pressing at a pres- 7 8 sure in excess of about 1,000 p.s.i. at a temperature of OTHER REFERENCES q abcfut 230 to about for about 9 mum and Oleesky; Handbook of Reinforced Plastics; [Reinhold firing saud cured mixture at a temperature 111 excess of Publishing Corp; 1964; 264 and 265; Sci. Lib. aboutgoo References Cited 5 MORRIS LIEBMAN, Primary Examiner.

UNITED STATES PATENTS L. T. JACOBS, Assistant Examiner 3,164,556 1/1965 Apley, et a1.

3,260,685 7/1966 Rice et a1. 106-39, 41, 50, 62; 260--37, 38 

